Lianja Cloud Server FAQ

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Can I use Lianja Cloud Server with my existing Web Servers?

Yes. Lianja Cloud Server can operate standalone and works as a traditional Web Server "out-of-the-box" but it also includes an Apache plugin mod_lianja for Linux and an ISAPI filter for IIS on Windows.

What about security, can I restrict what services are available from the Internet?

Yes. Lianja Cloud Server can be configured to enable or disable OData Read/Update requests as well as WebSocket Services. You can also configure a whitelist and blacklist for IP addresses.

Does Lianja Cloud Server support https and SSL certificates?

Yes. To use https you need to install the apache plugin mod_lianja on Linux or the ISAPI filter isapi_lianja on Microsoft Windows.

Do Visual FoxPro Server Pages only work on Windows?

No they run on Windows and Linux (both x86 and x86_64) and use the Lianja database and scripting engine that is embedded in the Lianja App Builder.

What JavaScript engine is Lianja Cloud Server using and is this cross-platform?

JavaScript Server Pages (.jssp pages) is a page processing service modeled on PHP server pages. The Lianja Cloud Server has the V8 JavaScript engine embedded into it with many built-in objects and functions as well as the Lianja database engine embedded within it. The V8 JavaScript engine is the same engine used in Node.js but we have ported it to Windows, Linux and Mac and integrated it in so it operates seamlessly as part of Lianja Cloud Server.

What would you recommend me to write my server pages in, Visual FoxPro, JavaScript or Python?

You can write them in whatever you feel comfortable with and have knowledge of. This reduces the learning curve for building polished custom Web Applications. All types of server pages are data-centric. You can call Lianja/VFP code directly from Server Pages using Lianja.execute() and Lianja.evaluate() which are described above in this article.

Why do I need to write server pages, I thought the Lianja App Builder would generate Web Apps and Mobile Apps?

The Lianja HTML5-JavaScript Web Client and the Lianja HTML5-JavaScript Mobile Client will run Apps developed in the Lianja App Builder if you have followed best practices and developed your App the way we have recommended using standard pre-built sections and gadgets. Many Apps can be built like this and will run without changes in the Web Client and Mobile Client.

How scalable is the Lianja Cloud Server?

Highly! You can load balance web connections across multiple App Servers. There is no practical limit to the number of connections that can be made and it is extremely fast.

Can I have a mixture of clients accessing and updating data concurrently e.g. desktop apps, web apps, mobile apps?

Yes, the underlying database and scripting engine is embedded in all of the Lianja products; Lianja App Center, Lianja SQL Server and Lianja Cloud Server.

If I wanted to develop a custom mobile app in a non-Lianja product that performs CRUD operations on my Lianja data how would I do that?

Mobile apps typically use OData calls to perform CRUD operations on a remote server data source. You would use the OData Service built into the Lianja Cloud Server to achieve this. The OData Service generates JSON and handles CRUD operations using JSON formatted data. We recommend jQuery, jQuery Mobile and Twitter Boostrap which we in fact use ourselves.

Does the Lianja OData Service handle JSONP so I can get around SOP (Same-Origin Policy) issues?

Yes. See the article on using OData with Lianja, the $callback=myfunction argument will wrap the JSON data that it returns by a function call.

Typically HTTP requests are stateless how can I maintain state between requests?

You can use the _SESSION[] or $_SESSION[] associative array which persists between HTTP requests.

Can I retrieve photos and other images in the Lianja database and display them in a web page?

Yes, both Visual FoxPro Server Pages (.rsp pages) and JavaScript Server Pages (.jssp pages) have a built-in function that will generate an HTML img tag which contains the image. This function is called base64_encode_image().

How do I store the photos or other images?

You use the objectRead() built-in function in conjunction with the _FILES[] or $_FILES[] associative array. Both Visual FoxPro Server Pages and JavaScript Server Pages handle multiple file uploads using HTTP POST and setup the _FILES[] or $_FILES[] array. You can store the photo directly in a Lianja database table using objectRead($_FILES[0].tmp_nam, object_field_name ) in JavaScript or objectRead(_FILES[0].tmp_nam, object_field_name) in Visual FoxPro scripting.

I need to store a large amount of photos can Lianja Cloud Server handle that?

Yes, the Lianja database engine is 64-bit on all supported platforms (including 32 bit ones). It supports huge table sizes up to 2^64. That's big!

I need to handle 10s of thousands of users, can Lianja Cloud Server be clustered?

Yes, on Linux you can set up Lianja Cloud Server in an Enterprise-class HA (High Availability) cluster consisting of 2 x load balancers, multiple App Servers and 2 x Data Servers with automatic failover and fallback. It can also handle real-time geographic off-site data replication. If you need help with this contact us as we have significant expertise in this area.

In a nutshell, what makes Lianja Cloud Server so much better than other solutions?

It is completely cross-platform (not just Windows, Linux x86 and x86_64 too), has a highly scalable embedded 64-bit database, has a small memory footprint and is a part of the Lianja APaaS so you have a single vendor providing support and updates. It is currently the only cross-platform solution for data-centric Visual FoxPro and JavaScript Server Pages.

If I purchase Lianja Cloud Server do I need to also purchase Lianja SQL Server?

No. Lianja Cloud Server includes Lianja SQL Server.

When will the Lianja Cloud Server be available?

The Lianja Cloud Server has already been released. As additional functionality is added and enhanced customers who purchase the Lianja APaaS subscription will receive these updates at no additional cost.

How much does Lianja Cloud Server cost?

Lianja Cloud Server pricing information can be found here.

We are a software development shop. What does ISV (Independent Software Vendor) pricing look like?

Lianja ISV pricing and qualification requirements can be found here.

Do you have any further questions?

If you have any questions not covered on this FAQ then contact us and ask us, we will be pleased to help you.